Known in the past has been a rod-less cylinder equipped with a guide mechanism and comprised of a cylinder tube having a slit in an axial direction, a piston fit in the cylinder tube, a piston mount at the outside of the cylinder tube, and a piston yoke passing through the slit and connecting the piston and piston mount thereby forming a moving member, wherein the slit is closed by inside and outside seal bands, and a slider guided by a guide mechanism is made to move back and forth by the moving member. The guide mechanism, as shown in PLT 1, is comprised of sliding guide-use grooves provided at the two sides of an outer circumferential part of a round cylinder tube and balls held in ballways provided at guide arms engaged with the same. In PLT 2, there has been known a mechanism comprised of guide rails attached to top surfaces of flange parts formed at a bottom part of a cylinder and guide members attached to the inside of a bottom end of a table and engaged with the same.